Internal combustion engines, including diesel engines, gasoline engines, gaseous fuel-powered engines, and other engines known in the art generate a complex mixture of air pollutants. The air pollutants are composed of gaseous compounds including, for example, the oxides of carbon, nitrogen, and sulfur (COX, NOX, and SOX), and solid compounds including, for example, hydrocarbons (HC). Due to increased awareness of the environment, exhaust emission standards have become more stringent, and the amount of air pollutants emitted to the atmosphere by an engine may be regulated depending on the type of engine, size of engine, and/or class of engine.
In order to comply with the regulation of engine emissions, some manufacturers have started using a diesel oxidation catalyst (DOC). A DOC generally consists of a substrate coated with a precious metal catalyst that converts gaseous and solid compounds to harmless substances. The DOC is generally located downstream of an engine's turbochargers, if so equipped, and upstream of an engine's muffler.
In some applications, the DOC substrate may need to be very large to help ensure it has enough surface area or effective volume to convert appropriate amounts of the gaseous and solid compounds. These large substrates, however, can be expensive and require significant amounts of space within the engine's exhaust system. In addition, the substrate may require placement at a precise location within the engine's exhaust flow for proper activation temperatures to be attained and for the exhaust to be evenly distributed across a face of the substrate. This spacing may further increase packaging difficulties of the exhaust system. When improperly sized and/or spaced, the substrate can restrict exhaust flow to some extent and thereby cause an increase in the pressure of exhaust exiting an engine. If this exhaust back pressure is too high, the breathing ability and subsequent performance of the engine could be negatively impacted.
The exhaust system of the present disclosure addresses one or more of the needs set forth above and/or other problems of the prior art.